Restoration of riparian vegetation on a mountain river degraded by historical mining and grazing

Riparian ecosystems in montane areas have been degraded by mining, streamflow alterations, and livestock grazing. Restoration of ecological and economic functions, especially in high-elevation watersheds that supply water to lower elevation urban and agriculture areas is of high priority. We investigated the response of riparian vegetation and bank stability following channel treatments and riparian habitat restoration along a segment of the upper Arkansas River south of Leadville, Colorado. The study area has been historically degraded by heavy-metal mining and is designated a U.S. Superfund site. Additionally, trans-basin water diversions and livestock grazing have contributed to channel widening and altered vegetation composition and cover. We used a before-after-control impact study design in four reaches with varied contamination and grazing history to assess restoration success. Before restoration, streambanks were dominated by graminoids and total vegetation cover varied among reaches with willow cover less than 16% in three reaches. Post-restoration, changes in total vegetation cover fell short of projected goals, but willow cover was greater than 20% in all study reaches. The increase in woody cover likely contributed to reduced erosion and vegetation encroachment post-restoration. Differences in functional group cover among reaches persisted post-restoration and may be attributed to soil contamination levels and low willow seed rain and dispersal. These results highlight the importance of setting realistic restoration goals based on elevation and past land use. We recommend further remediation of fluvial tailings with low vegetation cover and continued monitoring of willow height and cover to determine if further restoration activities are needed.     

毒性国度/塔溪矿区的未来——美国俄克拉荷马州渥太华县皮歇尔与卡丁矿区的案例研究

从社区层面探讨了40平方英里(约103km2)的塔溪矿区"超基金"污染场地(Superfund Site)的可持续规划设计以及应用策略。位于俄克拉荷马州渥太华县的塔溪矿区的状况表明联邦和州立管理机构在应对该地区长期以来的环境退化、有毒物质侵害以及环境公平问题上并没有取得明显成效。因此,附近的社区邻里、环境部门官员与学术团体积极合作,针对采矿遗留的大规模土堆、污染的河道、沉降的地面和塌陷的坑井等进行了长期的修复、再生和规划的探索。这个案例研究将证明,这种基于地方的矿区更新模式可以作为一个框架将社区诉求、环境整治和景观再生整合到一起。